Dehydration as used herein is the method of processing foods by drying them so thoroughly without cooking that the majority of the liquid content is removed. This is most successfully done at a very low, even heat such that the food product is not cooked and is dried thoroughly. Utilizing dehydration, foods can be prepared and stored during the growing season for year-round use without the necessity of sugars, jars, refrigeration and the other inconveniences normally associated with preservation of foods.
Dehydrated foods retain much of their natural nutrients and food value and in most cases retain more of these nutrients than in alternative methods of preservation. Most dehydrated foods can be returned to the natural state of appearance and taste by rehydration and can be used in their dehydrated state as a nutritious snack.
Historically, man has used enclosed heated spaces for cooking and/or storing foods such as ovens, warming bins, and heating-serving carts. Further, man has used closed containers to enclose food stuffs for particular or special treatments such as smoking. Examples of these containers and their various structural concepts necessary to accomplish the desired result are well known in the art. Prior art examples of some of these structures are included herewith for reference purposes.
U.S. Pat. No. 1,281,341, granted to Truitt, Mar. 6, 1917 discloses an electric oven having a heating element located in the lower portion of an insulated enclosure and including as an integral part thereof holes within the food supporting shelves to allow upward flow of heated air and a fan driven return chimney at the rear portion of the oven to cause the air to recirculate over the heating coils and retain a stable cooking temperature.
U.S. Pat. No. 2,179,256, granted to Gill, Nov. 7, 1939, deals with the heating, drying and sterilizing cabinet primarily for use with towels or the like in hospitals, barber shops, etc. Each shelf includes a heating element to assure uniform temperature throughout the cabinet and the shelves are constructed such that there is space for air to circulate around the shelves and the objects contained thereon. Further, the sterilizing cabinet of this reference includes means whereby air can be circulated into and out of the cabinet when the cabinet is closed and in use.
U.S. Pat. No. 2,561,517, granted July 24, 1951 to Ladge, discloses a dispensing cabinet wherein food stuffs, particularly breads and the like are stored and maintained warm for a considerable period of time. It is imperative that food kept under these conditions must not lose their moisture content and so therefore the cabinet makes provision for continual recirculation of the moist air within the cabinet and does not permit entrance or exit of the air.
U.S. Pat. No. 2,919,339, granted to Hilliker, Dec. 29, 1959, discloses a food service cart for use in hospitals or the like which incorporates as an integral part thereof a heating section having a heat storing element and a cooling section having a compressor and other cooling elements.
U.S. Pat. No. 3,127,499, granted Mar. 31, 1964 to Savio et al., discloses an electrically heated, forced air circulation oven and incorporates as an integral part thereof heating elements located around the entire interior of an insulated box and provides means for continuously circulating the heated air throughout the interior assuring a constant cooking temperature throughout the interior.
U.S. Pat. No. 3,458,686, granted July 29, 1969 to Gvozdjak is another example of an electric oven with heat circulation means therein and includes as an integral part, air directing baffles assuring that the heated air is uniformly distributed throughout the interior without having the upper portion of the oven substantially hotter than the lower portion. It is the desire, as stated in the patent, that the contents are consistently and efficiently heated to substantially the same cooking temperature.
U.S. Pat. No. 3,674,982, granted July 4, 1972 to Hoyt et al., discloses an elaborate zone controlled cook oven designed primarily for use on airplanes or the like wherein the desired mean temperature throughout each area or zone within an oven where frozen food is deposited is subject to independent control. Again, it is the intent and purpose of the structure to assure that the contents placed within the oven are subject to uniform heat and then maintained at a palatable heat until just prior to serving.
Thus, it can be seen, that although each of the structures hereinabove described with respect to prior art patented devices, each contain in the broad sense a containing or enclosed structure and a heating element or elements. Each is designed for a particular purpose, ie., either to continually recirculate the heated air within a cabinet to insure that the moisture content is retained or alternatively to provide a uniform temperature throughout the interior of the container for cooking.
Further prior art includes elaborate food dehydraters utilizing thermostatically controlled heating elements and fan forced circulation.
Because of the particular nature of dehydration of food stuffs it is necessary that the temperature at which the food is exposed is of a very low degree and of a constant nature. Too high a temperature will cause the food to cook or alternatively if the high temperature is combined with a rapid circulation of air, will cause the food to form a crust on the exterior thereof without completely drying the interior. The incomplete drying is often the cause of food spoilage. The food tends to deteriorate from the inside. It is also critical to have the food being dehydrated subjected to a constant and gentle flow of air without causing the above noted exterior crusting or cooking.
It is therefore an object of the present invention to provide a simple container for use in dehydration of foods wherein the structure is such that the operator need not have particular experience or expertise in the process to satisfactorily preserve the food and there is no danger of cooking the food.
It is further an object of the present invention to provide a food dehydrating device wherein the heating element and the integral provision for the constant circulation of the air within the cabinet are such that continuous attention is obviated. An operator need only place the food stuff upon the provided shelving and the structure of the cabinet itself in conjunction with the provided heating element will, upon being attached to the proper receptacle do the dehydrating in an efficient and satisfactory manner.
It is yet another object of the present invention to provide a cabinet which has as an integral part thereof means supporting the food containing shelves or drawers and further providing a means for carrying the heated air from the heating element which is located in the bottom of the container to the top in such a manner that the food located on the lowest shelf of the container is maintained at a slightly higher temperature than the food stuff at the top of the container.
Still another object of the present invention is to provide a dehydrater wherein air circulation is provided throughout the interior of the container and a simple mechanical means is provided whereby the temperature to which the food is subjected may be quickly and easily controlled by the operator.
It is still another object of the present invention to provide a combination of a heating element having a predetermined resistence with openings throughout the container for circulation of air. Outside air is admitted to the cabinet through restrictive openings and are determinative of the desired and optimal circulation of air for the dehydration of the product.